1. Field of the Invention
This invention relates to a method for the addition of an alkylene oxide to such an active hydrogen-containing compound as a polyalkylene imine or an unsaturated alcohol.
2. Description of the Related Art
The alkylene oxide adducts (alkoxylated compounds) of such active hydrogen-containing compounds as polyalkylene imines and unsaturated alcohols are widely used as raw materials for various detergents and chemical products. As a method for effecting the addition of an alkylene oxide, the practice of performing the reaction of an active hydrogen-containing compound with an alkylene oxide in the presence of an acid catalyst or a base catalyst. PCT International Publication 97/23,546, for example, discloses a method for the addition of a polyethylene oxide to a polyamine, and more particularly a method which comprises adding about 1 mol of ethylene oxide to 1 mol of the NH bond contained in a polyamine, adding a catalyst, and thereafter further adding a prescribed amount of ethylene oxide.
When an alkylene oxide is supplied to a reaction solution, the portion of the alkylene oxide which has been supplied in excess of the solubility of the reaction solution exists in the gas phase of the reaction vessel. The alkylene oxide in the gas phase, when the alkylene oxide concentration in the liquid phase falls below the solubility in consequence of the advance of an alkylene oxide addition reaction, is absorbed in the liquid phase and used to the further alkylene oxide addition reaction.
Under the reaction conditions such that the reaction solution has high viscosity, however, since the alkylene oxide present in the gas phase is absorbed slowly into the liquid phase, the liquid phase cannot secure sufficient supply of the alkylene oxide and the pressure of the reaction vessel falls with difficulty. As a result, the absorption of the alkylene oxide into the liquid phase forms a rate-determining step and incurs the problem of lowering the rate of the target reaction of the alkylene oxide with an active hydrogen-containing compound. The lowered rate of the reaction not only degrades the productivity but also causes formation of impurities and coloration of the reaction solution.
Further, the alkylene oxide addition reaction has the problem of by-producing a component that degrades the characteristic properties of the alkoxylated compound owing to the decomposition of the adduct formed and the reaction of the water present in the reaction system with the alkylene oxide.
It is, therefore, an object of this invention to provide a method for the production of an alkoxylated compound, which enables an alkylene oxide to be efficiently added to an active hydrogen-containing compound even when the reaction solution has high viscosity.
It is another object of this invention to provide a method for the production of an alkoxylated compound, which is capable of controlling the content of a by-product which forms a cause for the degradation of the characteristic properties of the alkoxylated compound.
This invention concerns a method for producing an alkoxylated compound by supplying an alkylene oxide to an active hydrogen-containing compound delivered to an agitating reaction vessel, characterized by a reaction solution in the process of an alkylene oxide addition reaction having highest viscosity of not less than 10 mPaxc2x7s, the reaction solution being stirred by the rotation of a vane or vanes continuously disposed in the vertical direction in the agitating reaction vessel, and the numerical value C represented by the following formula (1):
C=A/(h2xe2x88x92h1)xe2x80x83xe2x80x83(1) 
(wherein A denotes the length (m) of the vane or the vanes newly immersed by the supply of alkylene oxide, h1 denotes the height (m) of the liquid level before the supply of alkylene oxide, and h2 denotes the height (m) of the liquid level after the supply of alkylene oxide) being not less than 0.5.
In the addition of an alkylene oxide to an active hydrogen-containing compound, the absorption into the liquid phase of the alkylene oxide present in the gas phase can be promoted by stirring the neighborhood of the surface of the reaction solution so as to satisfy the conditions mentioned above. Even when the reaction solution has high viscosity, therefore, the alkylene oxide can be added highly efficiently to the active hydrogen-containing compound. Further, the amount of the by-product can be decreased because the reaction time can be shortened.
This invention further concerns a method for producing an alkoxylated compound by supplying an alkylene oxide to an active hydrogen-containing compound delivered to an agitating reaction vessel, characterized by the reaction solution being stirred by the rotation of a vane or vanes disposed continuously in the vertical direction in the agitating reaction vessel, the reaction solution being stirred to remove impurities and/or a solvent by the rotation of the vane or the vanes after the addition of alkylene oxide, and the numerical value Cxe2x80x2 represented by the following formula (2):
Cxe2x80x2=B/(h2xe2x88x92h3)xe2x80x83xe2x80x83(2) 
(wherein B denotes the length (m) of the vane or the vanes newly exposed to the gas phase in consequence of the decrease of the reaction solution, h2 denotes the height (m) of the liquid level after the supply of the alkylene oxide, and h3 denotes the height (m) of the liquid level after the treatment for removal of impurities or solvent) being not less than 0.5.
By stirring the neighborhood of the surface of the reaction solution so as to satisfy the conditions mentioned above after the addition of an alkylene oxide, it is made possible to deprive the reaction solution of the by-produced impurities or the solvent highly efficiently. Further, this invention concerns a method for producing an alkoxylated compound having an average addition number of not less than 40 mols of alkylene oxide by supplying an alkylene oxide to an alkenyl group-containing hydroxy compound in the presence of a catalyst, characterized by the reaction temperature (X), reaction time (Y), and catalyst concentration (Z) during the alkylene oxide addition reaction satisfying the following formula (3):
Numerical Value J=300+0.033X2Yxe2x88x926.5XY+300Z+330Y less than 1900xe2x80x83xe2x80x83(3) 
(wherein X denotes the reaction temperature (xc2x0 C.), Y denotes the reaction time (time (hr) for the introduction of alkylene oxide+time (hr) for aging), and Z denotes the catalyst concentration (the mass % of the catalyst relative to the theoretical quantity of the alkoxylated compound calculated from the quantities of a charged raw materials).
In the addition reaction of an alkylene oxide, by performing the addition reaction under conditions allowing the reaction temperature (X), the reaction time (Y), and the catalyst concentration (Z) to satisfy the specific relation, it is made possible to control the by-production of a polyalkylene oxide.
The foregoing aspects of the invention concerning the production of an alkoxylated compound may be implemented in combination. In the case of such a combination, the effects of the individual aspects of the invention can be manifested jointly.
The above and other objects, features, and advantages of the present invention will become clear from the following description of the preferred embodiments.